Submarine Topography Construction Method Based on Multi-Source Water Depth Data Integration

1. A computer implemented submarine topography construction method executed on a processor based on multi-source water depth data integration, characterized by comprising the steps as follows and in the following order: step 1: converting a historical submarine topography map into grid data; (1) vectorizing an original submarine topography map: scanning a paper pattern submarine topography map through a flatbed scanner, performing electronic vectorization on a plane topography map, and reserving depth attribute of each counter, wherein the vectorized electronic topography map needs to be perfectly matched with the plane topography map, the vectorized electronic topography map forms an electronic topography data set D 1 ={t1 i }, and each counter is composed of a water depth set {x1 j , y1 j , z1 j }, and t1 i ={x1 j , y1 j , z1 j }, wherein i and j are natural number; (2) adding feature auxiliary lines: checking the vectorized electronic topography map and adding auxiliary lines for regions having saddle topography and positive and negative value topography, wherein the auxiliary lines added are consistent with the trend of a vector line in the electronic topography map, and a data set D 2 ={t2 i } is formed after the auxiliary lines are added, wherein each counter t2 i is composed of a water depth set {x2 j , y2 j , z2 j }, and t2 i ={x2 j , y2 j , z2 j }; (3) converting the topography map into a grid: employing a Kriging gridding method to perform data conversion, wherein grid data G his (I,J) is formed after the conversion, wherein I, J represent water depth value; (4) re-charting a submarine topography map: for the grid after the conversion, re-charting a submarine topography map according to the same charting parameters as that of the plane topography map in step (1) to form a re-charted topography data set D 3 ={t3 i }, wherein each counter t3 i is composed of a water depth set {x3 j , y3 j , z3 j }, and t3 i ={x3 j , y3 j , z3 j }, and wherein the charting parameters refer to projective mode, coordinate system and counter spacing; or, method of overlapping, contrasting and evaluating conversion accuracy: contrasting the data sets formed in step (1) and step (4) through a map layer overlapping and contrasting method; (a) calculating the spatial distance between the old and new counters (t1 i ={x1 j , y1 j , z1 j } and t3 i ={x3 j , y3 j , z3 j }: d j =√{square root over ((x1 j −x3 j ) 2 +(y1 j −y3 j ) 2 )} point by point, (b) calculating the mean error value of the distance between the old and new counters: d _ = ∑ j = 1 n ⁢ d j , (c) when d >d, getting back to step (2) to re-add auxiliary lines, wherein d refers to a pre-determined error value of the distance between the old and new counters, when d ≦d, outputting a converted grid document G his (I,J), or, employing a method of extracting data of the same point and evaluating the conversion accuracy: in the grid data G his (I,J), extracting water depth value z4 j in sequence based on the coordinates (x1 j , y1 j ) of each counter t1 i ={x1 j , y1 j , z1 j } in the topography data set and in accordance with an inverse distance weighting method to form a new data set D 4 ={t4 i }, wherein each new water depth data t4 i is composed of a water depth point set, and t4 i ={x4 j , y4 j , z4 j }; (a) a method of extracting water depth data: reading t1 i ={x1 j , y1 j , z1 j } in sequence, querying the position in the grid document G his (I,J) according to the coordinates (x1 j , y1 j ), and calculating the water depth value z4 j of each point among four proximal points according to the inverse distance weighting method: z ⁢ ⁢ 4 j = ∑ I = k k + 1 ⁢ ∑ J = l l + 1 ⁢ w ( I , J ) × dep ( I , J ) ∑ I = k k + 1 ⁢ ∑ J = l l + 1 ⁢ w ( I , J ) w ( I , J ) = 1 ( x ⁢ ⁢ 1 i - x ( I , J ) ) 2 + ( y ⁢ ⁢ 1 i - y ( I , J ) ) 2 where, x (I,J) and y (I,J) are a coordinate value of the grid data; w (I,J) is a weighted value; and dep (I,J) is a water depth value in the grid document G his (I,J); (b) calculating the mean error value of the water depth between the old and new counters: z _ = ∑ j = 1 n ⁢  z ⁢ ⁢ 4 j - z ⁢ ⁢ 1 j  n ; (c) when z >z, getting back to step (2) to re-add auxiliary lines, wherein d refers to a pre-determined error value of the water depth between the old and new counters, when z ≦z, outputting the converted grid document G his (I,J), step 2: converting water depths of other sources into grids; (1) measuring the submarine water depth data by using multi-beam sensors, and gridding the measured submarine water depth data through the inverse distance weighting method to form grid data G mb (I,J); (2) measuring the submarine water depth data by using single-beam sensors, and gridding the measured submarine water depth data through a Kriging gridding method to form grid data G sb (I,J); (3) measuring the submarine water depth data by using a satellite altimetry and global topography system, and gridding the measured submarine water depth data through Gaussian spline interpolation or inverse distance weighting method to form grid data G oth (I,J); gridding the submarine water depth data measured through the different methods above by the same parameters, including interpolation method, interpolation parameters, coordinates, projection and water depth data measurement datum plane; step 3: evaluating the accuracy of the submarine water depth data measured through the different methods, wherein the following steps are employed to evaluate: (1) using a map layer overlapping and contrasting method to carry out overlapping and contrasting on the submarine water depth data measured through the different methods, and determining the accuracy thereof through the water depth difference of different grids in the water depth point of the overlapped region; (2) contrasting the original submarine water depth data if any, sorting according to the high-low sequence of the water depth accuracy, and reserving the water depth data having the highest accuracy; in case of no original submarine water depth data, taking precedence of the submarine water depth data measured through multi-beam or single-beam method, followed by the submarine water depth data reflected by the historical topography map and finally the submarine water depth data measured through satellite altimetry and global topography library method; step 4: integration, cutting and splicing on multi-source water depth data, wherein the following steps may be employed: (1) taking the water depth data having the highest accuracy determined in step 3 in the overlapped region through a map layer overlapping and contracting method, and correcting the data of the non-overlapped region through the mean error value Δd of the water depth data of the overlapped region; or, employing a gridding method to correct the error water depth data, i.e. constructing a water depth error grid G err (I,J) through a spline or Bezier curve according to the water depth difference data set D err ={t 1 } of the data having the highest accuracy determined in step 3 and other-source data in the same position of the overlapped region, and then using the error grid to correct the data of the non-overlapped region point by point; (2) reserving the data having the highest accuracy in the overlapped region and cutting other data to respectively form data grids G his (I,J), G mb (I,J), G sb (I,J) and G oth (I,J) after cutting; step 5: constructing multi-source water depth submarine topography and the grid, wherein the submarine topography is constructed through the following steps: (1) converting the data grids G his (I,J), G mb (I,J), G sb (I,J) and G oth (I,J) formed in step 4(2) into discrete water depth data D his ={t i }, D mb ={t i }, D sb ={t i } and D oth ={t i }; (2) re-constructing the submarine topography grids for the discrete water depth data in step 5(1) by employing a uniform gridding method to form a uniform data grid G fus (I,J); or, reading various water depth data grids formed in step 4(2) and integrating the grids to form a uniform data grid G fus (I,J); (3) re-charting a submarine topography map based on the integrated grid G fus (I,J), overlapping and contrasting the submarine topography map with the topography map in step 1, and evaluating the integrated data accuracy according to the method of method of overlapping, contrasting and evaluating conversion accuracy or the method of data extracting and evaluating conversion accuracy in step 1(4).